1. Field of the Invention
The present invention relates to a developing device and to a process cartridge for use in, for example, an electrophotographic image forming apparatus.
As employed herein, a xe2x80x9cprocess cartridgexe2x80x9d refers to a cartridge including at least one of a unit for charging an electrophotographic photosensitive member, a unit for developing a latent image formed on the electrophotographic photosensitive member, and a unit for removing developer remaining on the electrophotographic photosensitive member integrally formed with the electrophotographic photosensitive member in a cartridge. The cartridge can be attached to and detached from the main body of the electrophotographic image forming apparatus.
In addition, a xe2x80x9cdeveloping cartridgexe2x80x9d, described hereinbelow, refers to a cartridge including a unit for developing a latent image formed on an electrophotographic photoconductive drum using toner integrally formed with a toner frame for accommodating the toner in a cartridge, and is removably attached to an image forming apparatus main body.
In this specification, a xe2x80x9clongitudinal directionxe2x80x9d refers to a direction that is perpendicular to a conveyance direction of a recording medium and is in parallel with the surface of the recording medium. In addition, a xe2x80x9clateral directionxe2x80x9d refers to a direction perpendicular to the longitudinal direction.
2. Description of the Related Art
Hitherto, image forming apparatuses for forming multicolored images by electrophotographic methods have been proposed in which a plurality of developing cartridges for accommodating different-colored developers (toners) are arranged on a rotary selection mechanism (developing rotary) with respect to a photoconductive drum, which is an electrophotographic photosensitive member, a developing cartridge having a toner of a predetermined color accommodated therein is opposed to the photoconductive drum to effect developing, the developed image is transferred to a recording medium, and the developing and transferring operations are effected for each color to obtain the multicolored image. The developing cartridges are removably attached to the image forming apparatus main body so as to facilitate maintenance by a user.
Such a developing cartridge is formed by combining a developing frame for supporting developing members, such as a developing roller, a developing blade for controlling the thickness of toner coated on the developing roller, and a coating roller for applying the toner to the developing roller, and a toner frame having the toner accommodated therein into a cartridge so as to allow a reduction in size thereof.
In the above described developing cartridge, it is common for a supporting plate of the developing blade to be increased in its degree of straightness and flatness so that the developing blade (control member) for controlling the thickness of a developer on the developing roller (developer carrier) abuts equally against the developing roller along its length.
It is also common for both ends of the developing plate to be fixed by small screws so that the developing blade does not move with respect to a developing case.
In addition, a process cartridge has been proposed incorporating therein the developing device as the developing member.
It is an object of the present invention to provide a developing device and a process cartridge, each including a control member for reducing variations in an abutting force against a developer carrier. The control member controls the thickness of the developer on the developer carrier, as described above.
It is another object of the present invention to provide a developing device and a process cartridge in which a difference in abutting pressure of the developing blade on the developing roller may not be created by a flexure, etc., of the developing blade between the center and the end portion in the longitudinal direction of the developing blade, resulting in unevenness of image density.
It is a still another object of the present invention to provide a developing device including a developer carrier for carrying a developer; and a control member for controlling the thickness of the developer on the developer carrier, the control member including an abutting member abutting against a reference plane of a developing device main body; an elastic member overlapping the abutting member, the elastic member being urged toward the developer carrier, the width in the center portion of overlapped portions of the elastic member and the abutting member being wider than that in both ends thereof; and an overlap member overlapping the elastic member.
It is a further object of the present invention to provide a process cartridge including an image carrier; a developer carrier for carrying a developer; and a control member for controlling the thickness of the developer on the developer carrier, the control member including an abutting member abutting against a reference plane of a developing device main body; an elastic member overlapping the abutting member, the elastic member being urged toward the developer carrier, the width in the center portion of overlapped portions of the elastic member and the abutting member being wider than that in both ends thereof; and an overlap member overlapping the elastic member.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.